CLOCK

Purpose:    Specifies the type of system clock, installed in the computer.

Syntax:     CLOCK = <REAL|STANDARD>

By default: CLOCK = STANDARD

Note:

     In the default setting, DOS derives the current time and date using a
timer available with any personal computer. The initial state is then set
either by the real-time clock or equal to 00:00.00 1-1-1980. Setting CLOCK =
REAL makes the system to load a code, that directly works with the real-time
clock on time and date enquiries. In this mode less system memory is used
and the date range extends back to the year 1553. It is recommended to set
CLOCK = REAL in all cases when no compatibility with old DOS versions is
required with the symbol device CLOCK$.